Restart workflow in mistral

Hi
I am looking for a replacement for my current workflow engine and digging a little bit on mistral.

I have understood how you could run workflows, etc... what I am looking at is if there is a way to restart a workflow after it failed. Example, I have a workflow which executes task #1, executes a nested workflow with task #2 and #3, then a final task #4. The execution failed on task #3.

How is it possible in mistral to restart the same workflow with the input same parameter and run only the remaining tasks which is in this case #3 and the final task #4.

Other example, a nested workflow runs 6 concurrent provisioning of baremetal servers. In case of them fails, how does mistral know that it must only restart the failed server ?